ShowHBK Posted December 14, 2015 Report Share Posted December 14, 2015 I got a weird one for you all... below are the two posts that I have made on the RX-8 club as well as TL;DR in before RX-hate... just looking for second opinions. car drives ok (other then the vibration) and I don't have a CEL on TL;DR (to long, didn't read): Car's wheel, transmission, and shifter nob all vibrate violently 2000 RPM and 5000+ RPM. Idle is fine, crank and startup are fine. No CEL codes or flashing CEL... so no misfires drastic power loss at the top end. The engine is not building power like it should ******************************************************************************************* 06 Shinka - 93,000 Miles Coils, plugs, leads, clutch all original. No mods. All OEM parts. No CEL, no oil light, Coolant light on (bad sensor), TPMS on because its cold Started up fine today and I knew I needed to take a long trip this weekend so I picked up some 5w-20 conventional like I always do and checked the oil in the parking lot. I noticed the dipstick was down to about 1/4 level so I topped her off just a little hair above the fill line (maybe 2-3 millimeters above). When I went to start her up again there was a noticeable vibration on the shifter when I put it into reverse and started to exit the parking spot. I did not think much of it because it almost felt like the car does when you don't give it enough gas at low gears, just like that chugging vibration if anyone knows what I am talking about. I then put the car in first gear and drove off only to feel the same vibration again at exactly 2000 RPM but this time it was stronger though the shifter and I could feel it on the wheel. Thinking that was odd I stopped in an empty section of the parking lot and tried again in first gear and got exactly what i was expecting, more vibration at exactly 2000 RPM. The strange thing is the car runs fine anywhere above that or below that. Idle is fine with the occasional vibration from the Low fuel pressure resistor kicking in and when I took it out on the backroads a few minutes later the car ran fine and red lined for me with no issues or CEL flashing. it climbs through the power band just fine but something around the 6000K mark sounds like the engine has a swore throat almost because the noise it was making was deeper and had a little more bass to it. if you shift any other gear and somehow pass 2000 RPM you instantly get vibration. Here is the weird part... the car will still vibrate even it its not in gear and you hit 2000 RPM. I sat in my driveway and did a few test revs about 25 minutes ago and got the same results. Never once has the CEL come on and all I feel is vibration at the 2000 RPM mark. The clutch hooks up fine and shifts are what they always feel like, but I am completely baffled at what suddenly caused this. My understanding is that overfilling the oil can cause some problems for you by going into the intake, but I know it did not overfill the pan to the point where its puking into my intake. I know, I checked. Could it be engine mounts going bad suddenly and this is just a coincidence? ****************************************************************************************** ok, things just got weird and I am completely stumped. I am continuing my work and will update as I find things. I decided to drive her down on the trip thinking nothing was catastrophically wrong with the car and I am happy to report she drove 600 Miles this weekend with no major problems. Engine temps, oil pressure, and everything else was fine except the shifter was vibrating a lot more then normal. I checked my oil frequently and noticed no major issues. My gas mileage during the trip was awful which saw me getting just under 200 miles on each tank (yes, I filled up three times this weekend). I had the cruse set to 75 MPH and the RPM was steady the entire way but the car was drinking way to much fuel for a highway trip. This past summer I drove 900 miles in her and filled up three times averaging 300 miles to a tank. (sorry no MPG conversion) When I returned home on Sunday I took a look at the intake, inspected below the car, inspected the exhaust, inspected the oil pan, and checked the engine mounts but could find no apparent issues. I let her sit for a few hours to cool down and then I went for a drive down to the store. (here is where things get weird) during the trip, the car never once shook or vibrated once. the store is a short three minute drive down the road and the engine temp needle barley even moved so I know she was not warmed up. On my way back home as I was pulling into my driveway the vibration returned in full force in gear or out of gear. I tested the engine again with the car out of gear and the entire center column, shifter, and steering wheel all vibrated a good bit. I turned the car off, jacked it up, and inspected the bottom again and could find no issues again. This morning I was leaving for work and started her up again. (something to keep in mind is this car is my daily and I currently have no other ride, I would not normally continue to drive the car but I can't miss work during this time of year) When I began my morning commute everything seemed fine. No vibration, no shaking, no nothing. I figured things would happen eventually and sure enough as soon as the engine warmed up the vibration returned in full force at 2000 RPM in or out of gear. Something to note here: I am also feeling a HUGE lack of power through the power band. The engine just feels like its not pulling like it should. I have been driving this car for 3 years and autocrossing it a few times now, and I know what the power band should feel like and there is certainly a lack of power when the engine spins up. Only thing I have not pulled is the coils. I know they are original to the car, but could bad coils or plugs cause the entire thing to vibrate like this? I'm not getting misfires or any CEL to show signs of misfire. ************************************************************ I have determined the following: - The car vibrates hard at 2000 RPM when warmed up - Vibration occurs in or out of gear in the center console, wheel, and shifter - Vibration is constant, no knocking. - Clutch peddle is not vibrating and gear changes are normal - Clutch hooks up fine (from what I can feel) - Small vibrations can be felt above 4000 RPM - Engine is not pulling or producing power in the high RPM anymore - I am using 5w-20 Conventional oil and 93 gas ************************************************************ Possible causes? - Bad plugs, coils. leads? - Lose engine mounts that I can't see? - Transmission going bad? - Exhaust problems? loose exhaust? - Bad engine? engine going bad? ************************************************************ Any and all ideas or recommendations are always helpful. I will update this thread as soon as I find more information. Quote Link to comment Share on other sites More sharing options...
Smokey Posted December 14, 2015 Report Share Posted December 14, 2015 My rx8/renesis knowledge is limited, but when is the last time the plugs were changed? Any good/easy way to test coils and ignition? Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 14, 2015 Author Report Share Posted December 14, 2015 My rx8/renesis knowledge is limited, but when is the last time the plugs were changed? Any good/easy way to test coils and ignition? unfortunately according to this thread there is no guaranteed way to know/test coil functionality. The only sure way to know if a coil is bad is to look under them for white halos or rings. I plan on pulling them this weekend when I have some free time. The plugs and coils have never been replaced since I have owned the car and the manual says replace them every 35k, which is just under how long I have driven the car. http://www.rx8club.com/series-i-trouble-shooting-95/ignition-coil-testing-resistance-values-new-old-set-200423/ I know also that bad coils/plugs will (in most cases) have misfires followed by flashing CEL. Currently I lack a flashing CEL or misfires. Quote Link to comment Share on other sites More sharing options...
Patterson Posted December 14, 2015 Report Share Posted December 14, 2015 Bad mount would be my first guess if there is no Misfire CEL. Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted December 14, 2015 Report Share Posted December 14, 2015 Could the injectors cause a problem like this? You said it was getting poor fuel mileage, might be worth pulling the plugs and taking a look at them (yes I realize rotary plugs are different and should look different than normal plugs due to the oil burning nature of the motor). Maybe your injectors need cleaned. Also a compression test to see how the motor is doing is probably not a bad idea either. Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 14, 2015 Author Report Share Posted December 14, 2015 I will check all of this throughout the week when I find time and report back. Thanks for the suggestions everyone. If anyone thinks of anything else please feel free to chime in. Quote Link to comment Share on other sites More sharing options...
Miller Posted December 14, 2015 Report Share Posted December 14, 2015 Replace the rotary with an ls? Quote Link to comment Share on other sites More sharing options...
dsm_sleeper Posted December 14, 2015 Report Share Posted December 14, 2015 Replace the rotary with an ls? It was inevitable. Quote Link to comment Share on other sites More sharing options...
Geeesammy Posted December 14, 2015 Report Share Posted December 14, 2015 Check for codes still. Just because the engine light isn't on doesn't necessarily mean there are no codes stored or pending Quote Link to comment Share on other sites More sharing options...
BIGGU Posted December 14, 2015 Report Share Posted December 14, 2015 it sounds like motor mount of some sort but since it is a rotary, its probably the apex seals. Quote Link to comment Share on other sites More sharing options...
Robochan Posted December 15, 2015 Report Share Posted December 15, 2015 Drop a valve? Quote Link to comment Share on other sites More sharing options...
Cordell Posted December 15, 2015 Report Share Posted December 15, 2015 Get the correct rotory compression tool and check for fucked apex seal. Those also have a variable intakerunner that can quit working, should throw a CEL but you never know. Quote Link to comment Share on other sites More sharing options...
Second Gen Posted December 15, 2015 Report Share Posted December 15, 2015 Plugs - Not likely (But they always burn rich and worth replacing) coils - Ask around local to see if anyone has a set laying around Not - Apex seal unless it ate itself (I have had a couple and they just loose power or don't start) - Pull plug (One on each rotor) and use a small Maglite to shine into the plug hole. Usually can see if the apex went kaboom Doubt the computer will tell you anything, but worth a trip to the local auto store for free Cat's common problem for the REW's (I know this is a renesis) above 75K and might be an issue. Again maybe a code from the computer about an O2 issue?? (Really wondering about this being the cause!!) Lastly gl!! Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted December 15, 2015 Report Share Posted December 15, 2015 I may have a spare set of coils from my fc that you are welcome to though I believe it would require modification to work. Quote Link to comment Share on other sites More sharing options...
Patterson Posted December 15, 2015 Report Share Posted December 15, 2015 A worn cam lobe will act this way as well. Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 15, 2015 Author Report Share Posted December 15, 2015 I really do appreciate the suggestions everyone. Here is what I know so far - The vibration and shaking only occurs still at 2000 RPM and anywhere above 5000 RPM the engine refuses to build power. - This is a heat related problem or related to the engine warming up. The car will not shake or vibrate shortly or immediately after starting the engine. Tested for the past two days. - MPG and power are extremely low. I am used to getting ~220 miles to a tank but currently I am getting ~170 miles to a tank (sorry no MPG numbers) What do I plan on doing? Check for codes still. Just because the engine light isn't on doesn't necessarily mean there are no codes stored or pending I checked this last night. It was worth a try but there are no pending or existing codes. Get the correct rotory compression tool and check for fucked apex seal. Those also have a variable intakerunner that can quit working, should throw a CEL but you never know. I don't believe this is an apex seal issue to be honest. I have seen and heard videos online of what a blown renesis looks like and this is not the case. THe only way it could be my apex seals is if this is a sign they are going bad and maybe throwing the balance of the rotors off? I will call defined autoworks tonight and see of they offer compression tests for a decent price. I have always babied the car and have never had it serviced by Mazda after they fucked it up the first time so I am very reluctant to have anyone touch the car other than myself. I understand the idea of running a compression test with a psi meter or something similar by cranking the engine without fuel. I know you are looking for 3 even or close to even numbers for a good compression, but I have no idea where to hook up the meter or how to get an accurate reading. I may have a spare set of coils from my fc that you are welcome to though I believe it would require modification to work. According to a bit of research done the cons would outweigh the pros. Thanks for the offer but in my research they would fit the MSP-RE, but the power and fuel economy would go even lower. Everyone else recommends using plugs designed for the MSP-RE for best performance. ******************************************************** I will report back once I have a chance to jack the car up and check some things underneath more closely. I get paid this Friday so I will order the plugs/coils/leads then. Thanks once again for all the suggestions. Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 15, 2015 Author Report Share Posted December 15, 2015 It was inevitable. I knew someone would say something like that :doh: Quote Link to comment Share on other sites More sharing options...
Geeto67 Posted December 15, 2015 Report Share Posted December 15, 2015 A worn cam lobe will act this way as well. http://i2.kym-cdn.com/photos/images/facebook/000/000/681/what-you-did-there-i-see-it.thumbnail.jpg What about the MAF? could there be a piece of gunk in there that causes a slight misfire as the map hunts for the correction? Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted December 15, 2015 Report Share Posted December 15, 2015 Compression testing is fairly simple. It can be done with a standard compression tester, though the Mazda one is easier. If you care to try it yourself I could lend a hand. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 16, 2015 Report Share Posted December 16, 2015 Im goin with miller on this one, ls swap time. Quote Link to comment Share on other sites More sharing options...
Second Gen Posted December 16, 2015 Report Share Posted December 16, 2015 If temperature issue: Not plugs (Almost 100%) Coils - Still a maybe Cat's - Very possible Unlikely Apex seals (They typically get better when they warm up) But look on the bright side.. Now you can start sourcing the bigger motor (3 Rotor)!! Quote Link to comment Share on other sites More sharing options...
RyM3rC Posted December 16, 2015 Report Share Posted December 16, 2015 I had a 91 chevy truck that did the same thing. Turned out a coolant sensor had gone bad. Hope your fix is that simple. Any updates? Done any logging? Checked any parts? Any changes? Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 16, 2015 Author Report Share Posted December 16, 2015 ******** UPDATE ******* Thanks again for all the replies everyone. All the guys over on the RX8 club are hounding me to change plugs, coils, and leads ASAP. They explained to me that the plugs need to be replaced every 35k miles or I risk harming the CAT. I ordered a new set of everything and the parts will be here on Friday. I am beginning to think this is a possible exhaust issue? Last night I check a few other things. - MAF is not loose - no oil or fluid in the intake - coolant is fine (sensor is bad, will replace next paycheck) - I checked the upper intake and throttle body for damage but I was unable to find anything to note. - I could not jack the car up in my driveway last night because we had company over so I was unable to inspect anything else under the car. My Current Plan * Get the coils, plugs, leads replaced ASAP (Friday or Saturday) * Oil change? might as well? * Clean the air filter * Check my SSV? getting to it is a bitch, but might be worth it at this point. * Top off coolant * Inspect my exhaust line for lose bolts or anything * Maybe remove the CAT? worth inspecting the CAT for damage at this point? Quote Link to comment Share on other sites More sharing options...
ShowHBK Posted December 16, 2015 Author Report Share Posted December 16, 2015 Compression testing is fairly simple. It can be done with a standard compression tester, though the Mazda one is easier. If you care to try it yourself I could lend a hand. I might PM you to take you up on that offer, you free this weekend? If temperature issue: Not plugs (Almost 100%) Coils - Still a maybe Cat's - Very possible Unlikely Apex seals (They typically get better when they warm up) But look on the bright side.. Now you can start sourcing the bigger motor (3 Rotor)!! I almost feel the same way about this. Coils or plugs would throw up a CEL for sure if they were going bad and causing misfires. The car does not shake or rattle until it gets up to temperature and it only occurs at the RPM mentioned. I still don't have the expertise to know if a engine mount is bad/going bad/loose which might also be causing it. I would do a 20b swap in a millisecond if I could. paying for the new parts I currently ordered already cleaned me out until next paycheck. The timing of all this was horrible with the holidays and all. I had a 91 chevy truck that did the same thing. Turned out a coolant sensor had gone bad. Hope your fix is that simple. Any updates? Done any logging? Checked any parts? Any changes? Very well could be. My Coolant sensor has been bad for a while now and I always have a coolant light on the dash. It's a common problem in 8's where they sink to the bottom of the reservoir and give a false reading that you are low on coolant. The sensor is built into the bottle so the whole thing would have to be replaced. no new developments really. The car drives, shakes when it warms up, and the power it produces is poop (more poop then a rotary should be). Gas mileage is now in shit hole territory. my tank is just under a quarter gone and I only have driven 36 miles. I will keep the thread updated with anything I find, maybe pics if I take any so that others can maybe see something i'm missing. Im goin with miller on this one, ls swap time. God damnit.... Quote Link to comment Share on other sites More sharing options...
wagner Posted December 16, 2015 Report Share Posted December 16, 2015 Im goin with miller on this one, ls swap time. Says the person who put a traditinal small block chevy with a carb into a 4th gen f-body... Quote Link to comment Share on other sites More sharing options...
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